Coil car structure

ABSTRACT

A railcar unit has a pair of deep sidewalls and a cradle mounted between the sidewalls for carrying coils. The sidewalls span the distance between the two railcar trucks, and act as a pair of deep beams for carrying vertical loads. The deep sidewalls are arranged to extend above and below the centre sill of the cradle and to give vertical stiffness to the car. The centre sill is a straight through sill for carrying buff and draft loads between the couplers. The cradle is made from a set of cross bearers welded to the centre sill to form a series of segmented beams, covered by plating. The cross bearers are welded to the sidewalls at lap joints. The cross bearers are all of the same design and can be made from a rolled beam. The sidewalls have their deepest section at mid-span, and are tapered to a thinner section toward the end structure of the cars. The tapering includes provision of an access way between the railcar truck wheels and the sidewall to permit brake maintenance.

FIELD OF THE INVENTION

[0001] This invention relates to improvements in the structure railwaycars for carrying metal coils, commonly referred to as coil cars.

BACKGROUND OF THE INVENTION

[0002] Coils of steel sheet are often carried by rail cars. Coils can bemounted either longitudinally or transversely. In a longitudinalmounting, the axis of revolution of the coil is aligned to besubstantially parallel with the rolling, or longitudinal, direction ofthe rail car. A longitudinal mounting often has the appearance of asingle long trough with a number of moveable intermediate dividers. In atransverse mounting, the axis of revolution of the coil is alignedacross the tracks, that is, perpendicular to the rolling direction ofthe rail car. Transverse mounting cars have a number of parallel bunks,rather than one long trough. A bunk is generally V-shaped, and the coilsits in the bunk with the outer circumference of the coil tangent to theV at two points such that it cannot roll. The V-shaped bunks aregenerally lined with wood decking to act as cushioning, therebydiscouraging damage to the coils during loading or travel.

[0003] In earlier times flat cars were converted to function as coilcars by adding bunks on to the flat car deck to prevent the coils fromrolling off the deck during transport from the rolling mill to thecustomer. The basic structure of a flat car includes a main center sillthat is box shaped in cross-section. The center sill of this kind of caris the main structural member of the car and runs from one end couplingof the car to the other. The center sill is the primary load path of thecar both for longitudinal buff and draft loads from coupler to coupler,and for carrying the vertical load bending moment between the trucks. Awide deck is mounted above the center sill of this kind of car. Often,alternating cross-bearers and cross ties extend outwardly from thecentral sill. The cross bearers tend to be of deeper section and providethe majority of the support for the outboard regions of the deck.

[0004] Over time, the size and weight of coils that can be carried hasincreased. The flat car design has evolved to have stronger and biggermain sills, sometimes reinforced by doubled sections. Further, thecentral sill may not necessarily be of constant section, but may have a“fish belly” profile. That is, the depth of section of the centre sillcan increase toward the mid-section of the railcar to correspond to theincrease in bending moment at mid-span between the rail car trucks.Further, longitudinal stringers, in the form of I-beams or wide flangebeams have been located above the deck level to form the upper lip ofthe longitudinal bunk. In another step in the evolution of the flat cardesign, some or all of the flat decking can be replaced by canteddecking to form the V-shaped trough. In more recent times the flatdecking has been removed entirely, to leave a railcar having a dominantcentre sill, a pair of elevated outboard longitudinal beams,cross-bearers cantilevered out from the centre sill like ribs; andV-shaped decking to form the trough.

[0005] The present inventor has taken a different approach. Rather thanhaving a dominant center sill, the inventor employ a pair of outboardbeams of relatively deep section. The coil carrying bunk is thensupported at its lateral ends to extend between the two deep side beams,A car with a pair of deep beams, well separated also has superiorlateral bending resistance to a narrower car.

[0006] In terms of fabrication, it is advantageous to reduce the numberof different parts used in an assembly. To that end, it would beadvantageous to replace the traditional arrangement of alternatingcross-ties and cross-bearers with a single design of cross-bearer. Whenthe cross-bearer is designed conceptually as a cantilevered arm or rib,it is not uncommon for the root of the arm to be of a deeper sectionthan the tip, reflecting the relatively large moment that must becarried at the root of the arm. However, a tapered section is not asconvenient as a section of constant depth. A section of constant depthcan be produced by a rolling mill, and is less likely to have weldingdefects or irregularities than a fabricated section. By contrast, whenthe cross-bearer is in concept more akin to a beam supported at twoends, the use of a section of constant depth is not inappropriate.

[0007] The use of a deep side beam presents the opportunity forimproving the connection at the outboard tips of the cross-bearers.Formerly, the use of I-beam or wide flange beams at the upper and outerlips of the trough did not always present a convenient weldingarrangement. The cross-bearer end could be trimmed to match the profileof the I-beam web, or the flange of the I-beam could be trimmed backlocally to accommodate the cross-bearer tip. In either case thecross-bearer tip would butt against the I-beam section. When deep sidebeams are used, the beams themselves have intermediate verticalstiffeners to discourage the relatively thin webs of the beams frombuckling. At the same time, the stiffeners present a flat surface, inthe same plane as the plane of the web of the cross-bearer, againstwhich a lap joint can be formed. Not only can a better joint be formed,but the fit-up process in manufacturing is, in the view of the presentinventor, easier. That is, the pre-existing vertical stiffener of thebeam acts as a longitudinal stop for the outboard tip of thecross-bearer, automatically locating it in the correct position.

[0008] Access for brake maintenance on a car with deep side walls may belimited. To address this concern the present inventor has eased thedownward profile of the side beams to permit improved access to thebrakes between the trucks and the mid-span portion of the car.

SUMMARY OF THE INVENTION

[0009] The present invention provides, in a first aspect, a rail car forcarrying metal coils, comprising a pair of end structures each mountedon a rail car truck, a pair of side beams extending between the endstructures, and a transverse cradle, for cradling metal coils, mountedbetween the side beams. The cradle has a longitudinally extending lowcentral portion. The lowest point of the low central portion lies at aheight that is at least as high as the lowest extremity of the sidebeams.

[0010] In an additional feature of that aspect of the invention, therailcar has, at a transverse-section between said trucks, a secondmoment of area about a horizontal neutral axis, and the side beamscontribute at least half of the second moment of area of the section. Inanother additional feature of that aspect of the invention, the sidebeams of the rail car contribute at least three quarters of the secondmoment of area of the section. In a still further additional feature ofthat aspect of the invention, the side beams of the railcar contributeat least 90% of the second moment of area.

[0011] In still another further additional feature of that aspect of theinvention, at a transverse section between the trucks, the location ofthe maximum longitudinal tensile stress under a gravity load is in thelowest chord of one of the side beams.

[0012] In yet another additional feature of that aspect of theinvention, at a transverse section between the trucks, the location ofmaximum longitudinal compressive stress under a gravity load is in thehighest chord of one of the side beams. In still another additionalfeature of that aspect of the invention, the cradle has a center sillextending longitudinally along the low central portion.

[0013] In still yet another additional feature of that aspect of theinvention, the central sill has a top flange and a bottom flange, therail car has, at a transverse section between the trucks, a neutral axisfor bending under gravity loads, and the neutral axis lies at a heightthat is between the height of the top and bottom flanges.

[0014] In another additional feature of that aspect of the invention,the cradle includes cross-bearers connected to the side beams. In stillyet another feature of that aspect of the invention, in at least amedial portion of the rail car between the trucks, the cross bearers areof substantially uniform design. In a further feature of that aspect ofthe invention, at least a medial portion of the rail car between thetrucks is of the type chosen from the set of rail car types consistingof rail car portions that are free of cross-ties and rail car portionsin which the number of cross ties is fewer than two thirds as many ascross bearers.

[0015] In still a further additional feature of that aspect of theinvention, the rail car has a through centre sill of substantiallyconstant cross-section. In still yet a further additional feature ofthat aspect of the invention, over at least the medial portion of therail car, the cross-bearers are of substantially uniform design. Inanother further additional feature of that aspect of the invention, atleast the medial portion of the rail car is of a type chosen from theset consisting of types that are free of cross-ties, and types that haveless than two-thirds as many cross-ties as cross-bearers.

[0016] In another aspect of the invention, there is a rail car forcarrying metal coils comprising a pair of end structures each mounted ona rail car truck, a pair of side beams extending between the endstructures, a transverse sling, for cradling metal coils, slung betweenthe side beams, the rail car having a set of brakes, and at least one ofthe side beams having a relief permitting access to the brakes.

[0017] In an additional feature of that aspect of the invention, therelief is located adjacent the truck. In another additional feature ofthat aspect of the invention, the one beam has a relief adjacent each ofthe trucks. In still another additional feature of that aspect of theinvention, both the beams have reliefs adjacent the trucks.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] For a better understanding of the present invention and to showmore clearly how it may be carried into effect, reference will now bemade by way of example to the accompanying drawings, which show anapparatus according to the preferred embodiment of the present inventionand in which:

[0019]FIG. 1 is a top view of a prior art coil car.

[0020]FIG. 2 is a side view of the prior art coil car of FIG. 1.

[0021]FIG. 3a is a cross-sectional view on section ‘3 a-3 a ’ of theprior art coil car of FIG. 1.

[0022]FIG. 3b is the other cross-sectional view on section ‘3 b-3 b ’ ofFIG. 1.

[0023]FIG. 4 is a sectional view on section ‘4-4’ of the prior art coilcar of FIG. 1.

[0024]FIG. 5a is top view a rail car according to the present invention.

[0025]FIG. 5b is a top view of the rail car of FIG. 5a with deckingremoved to show the skeletal structure of the rail car.

[0026]FIG. 6 is a side view of half of the rail car of FIGS. 5a and 5 b.

[0027]FIG. 7 is a cross section of the rail car of FIGS. 5a and 5 b atmid span.

[0028]FIG. 8a is a cross section of the rail car of FIG. 5a at the mainbolster.

[0029]FIG. 8b is a cross sectional view of the rail car of FIG. 5btoward the end bulkhead.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0030] The description which follows, and the embodiments describedtherein, are provided by way of illustration of an example, or examplesof particular embodiments of the principles of the present invention.These examples are provided for the purposes of explanation, and not oflimitation, of those principles and of the invention. In the descriptionwhich follows, like parts are marked throughout the specification andthe drawings with the same respective reference numerals. The drawingsare not necessarily to scale and in some instances proportions may havebeen exaggerated in order more clearly to depict certain features of theinvention.

[0031] For the purposes of better understanding the present invention, anumber of s illustrations of a prior art rail car are included by way ofcomparison. The prior art rail car is indicated generally in FIGS. 1, 2,3 a, 3 b and 4 as P20. It has a pair of rail car end structures P22 andP24, each having a main bolster P26, A main center sill is indicated asP28. Ribs branch outwardly from main center sill P28 and are indicatedas cross-bearers P30 and thinner cross-ties P32. The outer tips ofcross-bearers P30 and cross ties P32 meet with one or other of a pair ofwide flange beams P34 and P36. A generally V-shaped deck P38 runs thelength of the car, spanning the pitches between cross-beams P30 andcross-ties P32 to terminate at end bulkheads P40 and P42. Main centersill P28 has a generally box-shaped rectangular section that has a deepcentral belly P44, shown in FIGS. 3a and 3 b. Main center sill P28 hasan upper flange P46 and a thick central lower flange P48.

[0032] In the particular embodiment illustrated the overall depth ofmain center sill P28 at central belly P44 is 28 inches. The weight ofmain center sill P28 is 150 lbs per lineal foot, and its width is 22inches over the lower flange P48. The thickness of bottom flange P48 is1 inch and the thickness or the remainder of main center sill P28 is ⅜inches thick. Wide flange beams P34 and P36 are 13.8 inches deep at 34.3lbs. per lineal foot each. The overall weight of section is roughly 261lbs. per lineal foot with a neutral axis in bending located 22.9 inchesabove top of rail, undeflected design height. The local neutral axis ofmain center sill P28 is located about 23.3 inches TOR, and the localneutral axis of each of the wide flange beams is located about 56.8inches above TOR. The second moment of area of the section shown in FIG.3a is about 24,300 in⁴. Of this, 50% can be attributed to the influenceof main center sill P28.

[0033] At the mid-span line of car P20, it is expected conceptually thata large coil, such as an 84 inch diameter coil, will tend to place thetop flange of cross bearers P30 in tension and the lower flange incompression.

[0034] In FIG. 3a, wide flange P36 has been trimmed locally to admit thedistal tip P50 of cross-bearer P30, such that the end of the tapered webP52 and upper flange P54 of cross-bearer P30 abut the vertical web ofwide flange beam P36. Cross beam P30 and wide flange P36 are filletwelded together in this orientation. A similar arrangement is shown inFIG. 3b for cross-tie P32 and wide flange P34.

[0035] By contrast, an example of a rail car embodying the presentinvention is illustrated S in FIG. 5a. For the purposes of conceptualexplanation the embodiments illustrated in FIGS. 5a, 5 b, 6, 7, 8 a and8 b, the major structural elements are both symmetrical about thelongitudinal centerline of the car (as designated by axis CL) andsymmetrical about the mid-span transverse section of the car, indicatedas TS. In reality a number of secondary and tertiary brake fittings,handrails, brackets, cables and other ancillary features that do nothave appreciable effect on the structural performance of the car may notnecessarily be symmetrical about either centerline.

[0036] A rail car is indicated generally as 20. It has a pair of endstructures 22 and 24 for mounting on a pair of rail car trucks 26 and 28respectively. A pair of left and right hand side beams 30 and 32 extendbetween end structures 22 and 24, and form the main longitudinalstructural elements of rail car 20 for resisting gravitational loads. Acradle 34 is hung between beams 30 and 32. Cradle 34 resembles a trough,and is shaped to cradle steel coils, or other similar loads, between itsinwardly and downwardly sloping shoulders 36. Shoulders 36 are linedwith wooden decking 37 placed to accommodate coils ranging between 30and 84 inches in diameter. When coils are loaded in cradle 34 they arediscouraged from longitudinal sliding by end bulkheads 35 and bymoveable bulkheads 38 whose locating pins seat in the indexed aperturesof left and right hand locating plates 39.

[0037] The structure of cradle 34 includes a center sill, 40,cross-bearers 42 extending between center sill 40 and one or the otherof side beams 30 and 32, and deck plates 44. Deck plates 44 includeright and left hand slope plates 46, and 48 of shoulders 36, welded tothe upper flanges of cross-bearers 42 and to the upper flange 50 ofcenter sill 40. Center sill 40 includes, in addition to upper flange 50,a pair of parallel vertical webs 52 and 54 and a lower flange 56. Centersill 40 is a through-center-sill, that is, it runs from one end of railcar 20 to the other, and is of substantially constant section throughoutits length. Internal gussets 57 are welded inside center sill 40 toprovide web continuity at each cross-bearer location. Center sill 40 hasan overall depth of 12.719 inches. Upper flange 50 is 15 inches wide and0.50 inches thick. Lower flange 56 is 16 inches wide and 0.50 inchesthick. Vertical webs 52 and 54 are each 11.719 inches high and 0.375inches thick. The overall weight of the section is 82.3 lbs per linealfoot, and its local moment of inertia in longitudinal bending, that isits second moment of area about its transverse neutral axis, is 664 in⁴.

[0038] Since rail car 20 is symmetrical, for the purposes of the presentdescription it will be understood that the structure of side beams 30and 32 is identical. Each has an upper flange assembly 70, a lowerflange assembly 72, and webbing 74. Examining each of these in turn,upper flange assembly 70 has a top chord member in the nature of ahollow rectangular steel tube 76, upon which pin locating plate 39 ismounted. Plate 39 has an inwardly extending perforated tongue, 80, theperforations having a constant pitch, and being of a size and shapesuitable for engagement by the locating pins of moveable bulkheads 38.Also located intermittently along a more outboard region of plate 39 aretie-down eyes 84 for locating a cowling or cover to protect coilsmounted on coil car 20 from being exposed to the rain and snow. Lowerflange assembly 72 includes a main lower sill member in the nature of ahollow rectangular tube 86 to which a ¾″ thick steel lower sillreinforcement 88 has been added. Webbing 74 includes a substantiallyvertical steel web 90 welded at lap joints to the respective outer facesof steel tube 76 and rectangular tube 86. Vertical braces 92 extendbetween tubes 76 and 86 along the inner face of web 90 at regularspacings along the length of beams 30 and 32. A cantilevered walkway 94is mounted on brackets 98 located on the outboard face of web 90.

[0039] Over the mid span section of car 20, that is, the portion of car20 at which side beams 30 and 32 have their maximum depth, the overallsecond moment of area of each side beam 30 or 32 is about 14,800 in⁴.The weight of each side beam section is about 100 lbs. per lineal foot.Each of side beams 30 and 32 provides just over 45% of the total secondmoment of area of the mid span section of car 20.

[0040] The joining of cradle 34 to each of side beams 30 or 32 istypically as shown in FIG. 7. Deck Plate, 44 has a vertical upturned lip102 that is welded along the inwardly facing side of steel tube 76. Theweb 104 of cross bearer 42 extends beyond the ends of its upper andlower flanges 106 and 108 and is cut on a mitre to yield a substantialtab 110 suitable for welding in a lap joint to the longitudinally facingside 112 of vertical brace 92. The joint is welded at a fillet along thecorner of vertical brace 92 on one face of tab 110, and at a filletalong the distally extreme edge of tab 110 to side 112. In this way thejoint is intended to place the weldmetal predominantly in shear. Web 104also has intermediate gussets 114 to provide reinforcement in the regionof wooden decking 37. Wooden decking 37 is provided for the knownpurpose of cushioning metal coils loaded in car 20, as noted above.

[0041] Considering the side view of car 20 shown in FIG. 6, moving awayfrom the mid span centerline of car 20 on Transverse Section TS, thesection of greatest depth ends at a point designates as ‘X’. Lower sillreinforcement 88 ends, and hollow rectangular tube 86 is obliquelytruncated and welded to a doglegged upsweep flange 120. Flange 120follows the lower edge of web 90 as it narrows in a transition portion121 from the deep, mid span portion, 122 to the narrow, or shallow, endstructure portion 124, the upward sweep of flange 120, reaching a heightsufficient to clear trucks 26 and 28, as the case may be. The upperportion 130 of the dog leg has an exaggerated, or extended, reach toyield a relief, or accessway, indicated generally as 132 between thenear wheel 134 of truck 26 or 28, and the truncated end of lower silltube 86. This extended recess facilitates maintenance and repair ofoperating mechanisms of car 20, such as brake linkages. It also makesfor a more efficient use of material since the depth of section requiredat mid span is generally greater than that required near the ends of thespan for a simply supported beam. This permits a saving in weight.

[0042] Moving still further toward the end of car 20, the accumulatedvertical shear load in side beams 30 and 32 is carried to trucks 26 and28 of end structures 22 and 24, as shown in the sectional view of FIG.8a. Main bolster 140 has the form of a laterally extending irregular boxwith a pair of spaced apart, substantially parallel webs 142 and 144 ofsignificant depth. Webs 142 and 144 extend fully between a stepped lowerflange and a sloped upper flange 146 underlying deck plate 36. Webs 142and 144 have an extending tab 148 that reaches under and supports upperflange assembly 70, abuts the inside face of web 90, and also abuts thetop face of upswept flange 120.

[0043] In alternative embodiments of the invention to that shown, itwould be possible to design a car having a cradle with either a stepperor a shallower slope, with consequent alteration of the height of thecenter sill relative to the side beams. However, given the relativelyhigher pliability of the center sill under vertical bending loads ascompared to the side beams, it is undesirable for the chord of maximumstress (and therefore strain) to be in the lower flange of the centersill. To that end, the lower flange of the center sill, that is, itslowest extremity, is no lower than the lowest extremity of the sidebeams. Similarly, the highest compressive stress due to vertical loadwill occur in the highest portions to top chord assembly 70.

[0044] S In terms of carrying compressive longitudinal loads betweencoupler ends, it is advantageous to retain a straight through sill. Thisimplies a relatively high sill since standard coupler height is 33inches above top of rail to the center of the coupler.

[0045] In the embodiment illustrated, the centroid of area of car 20 isat a height just below the top of top flange 50, within the profile ofcenter sill 40. As such, center sill 40 plays only a small role inresistance to vertical bending.

[0046] It is possible to benefit from simplified production when all thecross bearers are of the same design, but some benefits can be obtainedeven when some cross ties remain, whether they are half as numerous, twothirds as numerous, one third as numerous as the cross bearers or someother fraction.

[0047] A preferred embodiment has been described in detail and a numberof alternatives have been considered. As changes in or additions to theabove described embodiments may be made without departing from thenature, spirit or scope of the invention, the invention is not to belimited by or to those details, but only by the appended claims.

I claim:
 1. A rail car for carrying metal coils, comprising: a pair ofend structures each mounted on a rail car truck; a pair of side beamsextending between said end structures; a transverse cradle, for cradlingmetal coils, mounted between said side beams; said cradle having alongitudinally extending low central portion; the lowest point of saidlow central portion lying at a height that is at least as high as thelowest extremity of said side beams.
 2. A railcar as claimed in claim 1wherein said railcar has, at a transverse-section between said trucks, asecond moment of area about a horizontal neutral axis, and said sidebeams contribute at least half of said second moment of area of saidsection.
 3. The rail car of claim 2 wherein said side beams contributeat least three quarters of said second moment of area of said section.4. The railcar of claim 3 wherein said side beams contribute at least90% of said second moment of area.
 5. The rail car of claim 1 wherein ata transverse section between said trucks the location of maximumlongitudinal tensile stress under a gravity load is in the lowest chordof one of said side beams.
 6. The rail car of claim 5 wherein at atransverse section between said trucks the location of maximumlongitudinal compressive stress under a gravity load is in the highestchord of one of said side beams.
 7. The rail car of claim 1 wherein saidcradle has a center sill extending longitudinally along said low centralportion.
 8. The rail car of claim 7 wherein said central sill has a topflange and a bottom flange, said rail car has, at a transverse sectionbetween said trucks, a neutral axis for bending under gravity loads, andsaid neutral axis lies at a height that is between the height of saidtop and bottom flanges.
 9. The rail car of claim 1 wherein said cradleincludes cross-bearers connected to said side beams.
 10. The rail car ofclaim 9 wherein in at least a medial portion of said rail car betweensaid trucks, said cross bearers are of substantially uniform design. 11.The rail car of claim 10 wherein at least a medial portion of said railcar between said trucks is of the type chosen from the set of rail cartypes consisting of (a) rail car portions that are free of cross-ties;and (b) rail car portions in which the number of cross ties is fewerthan two thirds as many as cross bearers.
 12. The rail car of claim 1wherein said rail car has a through centre sill of substantiallyconstant cross-section.
 13. The rail car of claim 12 wherein over atleast the medial portion of rail car said cross-bearers are ofsubstantially uniform design.
 14. The rail car of claim 12 wherein atleast the medial portion of said rail car is of a type chosen from theset consisting of (a) types that are free of cross-ties; and (b) typesthat have less than two-thirds as many cross-ties as cross-bearers. 15.A rail car for carrying metal coils comprising: a pair of end structureseach mounted on a rail car truck; a pair of side beams extending betweensaid end structures; a transverse sling, for cradling metal coils, slungbetween said side beams said rail car having a set of brakes; at leastone of said side beams having a relief permitting access to said brakes.16. The rail car of claim 15 wherein said relief is located adjacentsaid truck.
 17. The rail car of claim 15 wherein said one beam has arelief adjacent each of said trucks.
 18. The rail car of claim 15wherein both said beams have reliefs adjacent said trucks.